[PATCH] ima: kexec: Add RCU read lock protection for ima_measurements list traversal

[Breno Leitao]

Fix a potential RCU issue where ima_measurements list is traversed using
list_for_each_entry_rcu() without proper RCU read lock protection. This
caused warnings when CONFIG_PROVE_RCU was enabled:

  security/integrity/ima/ima_kexec.c:40 RCU-list traversed in non-reader section!!

Add rcu_read_lock() before iterating over ima_measurements list to ensure
proper RCU synchronization, consistent with other RCU list traversals in
the codebase.

Signed-off-by: Breno Leitao <leitao at debian.org>
Fixes: 7b8589cc29e7 ("ima: on soft reboot, save the measurement list")
---
 security/integrity/ima/ima_kexec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 52e00332defed39774c9e23e045f1377cfa30d0c..3b17ddb91d35ac806aedd2ee970ff365675dac0b 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -37,6 +37,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 
 	memset(&khdr, 0, sizeof(khdr));
 	khdr.version = 1;
+	rcu_read_lock();
 	list_for_each_entry_rcu(qe, &ima_measurements, later) {
 		if (file.count < file.size) {
 			khdr.count++;
@@ -46,6 +47,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer,
 			break;
 		}
 	}
+	rcu_read_unlock();
 
 	if (ret < 0)
 		goto out;

---
base-commit: f488649e40f8900d23b86afeab7d4b78c063d5d1
change-id: 20241104-ima_rcu-ee83da87d050

Best regards,
-- 
Breno Leitao <leitao at debian.org>